1. Field of the Invention
The present invention relates to a method of producing an electrophotographic photosensitive member, a process cartridge, and an electrophotographic apparatus.
2. Description of the Related Art
An electrophotographic photosensitive member containing an organic photoconductive substance (charge-generating substance) has been frequently used as an electrophotographic photosensitive member to be mounted on an electrophotographic apparatus. In an electrophotographic process, a cleaning step of removing transfer residual toner with a cleaning blade has been required to reduce a contact stress (coefficient of friction) between the cleaning blade and the electrophotographic photosensitive member in order that the occurrence of a phenomenon such as the squeaking of the cleaning blade or the turn-up of the cleaning blade may be suppressed.
The incorporation of a siloxane-modified resin having a siloxane structure in its molecular chain into the surface layer of the electrophotographic photosensitive member, which is brought into contact with a contact member (such as the cleaning blade), has been proposed for reducing the contact stress of the electrophotographic photosensitive member. Japanese Patent Application Laid-Open No. 2009-037229 discloses a technology involving incorporating a resin obtained by building a siloxane structure in a polycarbonate resin into the surface layer to reduce the contact stress (coefficient of friction) between the electrophotographic photosensitive member and the cleaning blade.
The surface layer of the electrophotographic photosensitive member is formed by: applying, onto a support or the like, a surface-layer coating solution obtained by dissolving or dispersing a binder resin or the like in a solvent to form a coat; and drying the coat. In addition, the solvent is selected in consideration of the solubility of the binder resin or the like, the absence of influences on electrophotographic characteristics, and the absence of the whitening, sagging, or the like of the coat at the time of its coating. As described above, from the viewpoint of compatibility between the electrophotographic characteristics and coatability, various investigations have been conducted on the solvent to be used as the solvent of the coating solution. Japanese Patent Application Laid-Open No. 2001-343767 proposes a method of producing an electrophotographic photosensitive member free of whitening at the time of coating and having electrophotographic characteristics comparable to or better than those in the case where a halogen-based solvent is used, the method involving using an aromatic hydrocarbon and ethylene glycol dimethyl ether as solvents of a charge-transporting-layer coating solution. Japanese Patent Application Laid-Open No. H06-123987 proposes that a drying temperature at the time of the production of an electrophotographic photosensitive member and the boiling point of a solvent to be used in a photosensitive-layer coating solution be regulated for suppressing the defects of a coat.
In Japanese Patent Application Laid-Open No. 2009-037229 or the like, in the production of an electrophotographic photosensitive member containing, in its surface layer, a resin having a siloxane structure, a solvent to be used in a surface-layer coating solution contains a halogen-based solvent such as monochlorobenzene from the viewpoints of the solubilities of the resin having a siloxane structure and any other material. In recent years, however, the relevance of a chemical substance to an environment has been attracting attention, and the management of the chemical substance and the regulation of its amount of emission have been enhanced. As part of the enhancement, the replacement of the halogen-based solvent with a non-halogen-based solvent has been progressing. In addition, the halogen-based solvent must be recovered separately from the non-halogen-based solvent upon waste liquid recovery and hence productivity is liable to reduce. In view of the foregoing, its replacement with the non-halogen-based solvent has been demanded. Examples of the non-halogen-based solvent suitable for use in the surface-layer coating solution for the electrophotographic photosensitive member include xylene and toluene.
However, in the case where toluene or xylene is used as the solvent of the surface-layer coating solution containing the resin having a siloxane structure for reducing the contact stress of the surface layer, a reducing effect on an initial coefficient of friction is not sufficiently obtained as compared with that in the case where monochlorobenzene is used, and hence the initial coefficient of friction needs to be reduced.